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Babel for of loop transpilation performance

I use the for of loop often for readability and ease of writing code, but after transpiling with babel, i found it bloats up code and am now worried about performance.
Here is what I mean
Input Code
const obj = {
a: 2,
bar: 'baz',
identity: x => x
};
for (const [ key, val ] of Object.entries(obj)) {
console.log(key, val);
}
Output Code
'use strict';
var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }();
var obj = {
a: 2,
bar: 'baz',
identity: function identity(x) {
return x;
}
};
var _iteratorNormalCompletion = true;
var _didIteratorError = false;
var _iteratorError = undefined;
try {
for (var _iterator = Object.entries(obj)[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
var _step$value = _slicedToArray(_step.value, 2),
key = _step$value[0],
val = _step$value[1];
console.log(key, val);
}
} catch (err) {
_didIteratorError = true;
_iteratorError = err;
} finally {
try {
if (!_iteratorNormalCompletion && _iterator.return) {
_iterator.return();
}
} finally {
if (_didIteratorError) {
throw _iteratorError;
}
}
}
obviously, the transpiled for of loop has much more code...
But my question is, should i stop using the for of loop because of possible "performance issues" with transpiled code (babel using iterators, etc.. to do a simple loop), and if so, what should I use instead?

This sounds like a generic 'should I stop using X because of possible performance issues?'
If X isn't causing performance issues now, and you don't have any evidence to show it'll cause performance issues in future, keep using it.
If it is or will cause performance issues, look for alternatives.
In this case of X being for..of then your alternatives are based on writing more code with the same behaviour.
Your example specifically iterates over an Object, so ignoring the fact for..of also supports iterating over sets and arrays, you only need to write slightly more code to iterate over the object properties:
for (const [ key, val ] of Object.entries(obj)) {
console.log(key, val);
}
Object.keys(obj).forEach(function(key) {
const val = obj[key];
console.log(key, val);
});
// You could also stick with a `for` loop (but note this isn't restricted to
// the object's 'own' properties in the same way as values() and entries()
for (const key in obj) {
const val = obj[key];
console.log(key, val);
}

Easy way to set javascript object multilevel property?

I am trying to create a javascript object like
var allUserExpiry={};
allUserExpiry[aData.userId][aData.courseId][aData.uscId] = aData;
But I am getting an error like allUserExpiry[aData.userId] undefined.
Is there a way, whereby I can set multi-level JS-Object keys? or is it important that I should go by doing allUserExpiry[aData.userId]={}, then allUserExpiry[aData.userId][aData.courseId]={} ?
Please let me know if there are any utility functions available for the same.

No, there is no way to set "multilevel keys". You need to initialize each object before trying to add properties to it.
var allUserExpiry = {};
allUserExpiry[aData.userId] = {}
allUserExpiry[aData.userId][aData.courseId] = {}
allUserExpiry[aData.userId][aData.courseId][aData.uscId] = aData;

Using Computed property names from ES6, it is possible to do:
var allUserExpiry = {
[aData.userId] = {
[aData.courseId]: {
[aData.uscId]: aData
}
}
};
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#Computed_property_names

Simply use loadash,
let object = {};
let property = "a.b.c";
let value = 1;
_.set(object, property, value); // sets property based on path
let value = _.get(object, property, default); // gets property based on path

Or you can do it:
function setByPath(obj, path, value) {
var parts = path.split('.');
var o = obj;
if (parts.length > 1) {
for (var i = 0; i < parts.length - 1; i++) {
if (!o[parts[i]])
o[parts[i]] = {};
o = o[parts[i]];
}
}
o[parts[parts.length - 1]] = value;
}
And use:
setByPath(obj, 'path.path2.path', someValue);
This approach has many weak places, but for fun... :)

Why not just do this?
var allUserExpiry={};
allUserExpiry[aData.userId] = {aData.courseId: {aData.uscId: aData}};

I have a pretty hacky but short way of doing it in IE9+ as well as real browsers.
Given var path = 'aaa.bbb.ccc.ddd.eee'; where path is what your intending to make into an object and var result = {}; will will create the object {aaa: {bbb: {ccc: {ddd: {eee: {}}}}}
result = {}
path.split('.').reduce(function(prev, e) {
var newObj = {};
prev[e] = newObj;
return newObj;
}, result);
will store the object in result.
How it works:
split('.') converts the input into ['aaa', 'bbb', 'ccc', 'ddd', 'eee']
reduce(function (...) {...}, result) runs through the array created by split, and for each entry will pass along a returned value to the next one. In our case we pass the new object through after adding the new object to the old one. This creates a chain of objects. reduce returns the last object you return inside of it, so we have to defined result beforehand.
This relies on using references so it won't be immediately clear how it works if you're expecting your code to be maintained by anyone else and should probably be avoided to be honest, but it works at least.

You can also use the following to create the initial structure:
var x = function(obj, keys) {
if (!obj) return;
var i, t;
for (i = 0; i < keys.length; i++) {
if (!t) {
t = obj[keys[i]] = {};
} else {
t[keys[i]] = {};
t = t[keys[i]];
}
}
};
var a = {};
x(a, ['A', 'B', 'C', 'D', 'E', 'F']);

Another approach without strings or array as argument.
function fillObject() {
var o = arguments[0];
for(var i = 1; i < arguments.length-1; i++) {
if(!o.hasOwnProperty(arguments[i])) {
o[arguments[i]] = {};
}
if(i < arguments.length-2) {
o = o[arguments[i]];
}else {
o[arguments[i]] = arguments[i+1]
}
}
}
var myObj = {"foo":{}};
fillObject(myObj,"back","to","the","future",2);
console.log(JSON.stringify(myObj));
// {"foo":{},"back":{"to":{"the":{"future":2}}}}
But I wouldn't use it :-) It's just for fun.
Because I don't like too much intelligent algorithm. (If it was in this category)

Using lodash you can do this easily (node exists and empty check for that node)..
var lodash = require('lodash-contrib');
function invalidateRequest(obj, param) {
var valid = true;
param.forEach(function(val) {
if(!lodash.hasPath(obj, val)) {
valid = false;
} else {
if(lodash.getPath(obj, val) == null || lodash.getPath(obj, val) == undefined || lodash.getPath(obj, val) == '') {
valid = false;
}
}
});
return valid;
}
Usage:
leaveDetails = {
"startDay": 1414998000000,
"endDay": 1415084400000,
"test": { "test1" : 1234 }
};
var validate;
validate = invalidateRequest(leaveDetails, ['startDay', 'endDay', 'test.test1']);
it will return boolean.

Another solution using reduce function (thanks Brian K).
Here we created a get/set to general proposes. The first function return the value in any level. The key is splited considering the separator. the function return the value refered from last index in the key's array
The second function will set the new value considering the last index of the splited key
the code:
function getObjectMultiLevelValue(_array,key,separator){
key = key.split(separator || '.');
var _value = JSON.parse(JSON.stringify(_array));
for(var ki in key){
_value = _value[key[ki]];
}
return _value;
}
function setObjectMultiLevelValue(_array,key,value,forcemode,separator){
key.split(separator || '.').reduce(function(prev, currKey, currIndex,keysArr) {
var newObj = {};
if(prev[currKey] && !forcemode){
newObj = prev[currKey];
}
if(keysArr[keysArr.length-1] == currKey){
newObj = value;
prev[currKey] = newObj;
}
prev[currKey] = newObj;
return newObj;
}, _array);
return _array;
}
//testing the function
//creating an array
var _someArray = {a:'a',b:'b',c:{c1:'c1',c2:{c21:'nothing here...'}}};
//a multilevel key to test
var _key = 'a,a1,a21';
//any value
var _value = 'new foo in a21 key forcing replace old path';
//here the new value will be inserted even if the path exists (forcemode=true). Using comma separator
setObjectMultiLevelValue(_someArray,_key,_value,true,',');
console.log('_someArray:');
console.log(JSON.stringify(_someArray));
//inserting another value in another key... using default separator
_key = 'c.c2.c21';
_value = 'new foo in c21 key';
setObjectMultiLevelValue(_someArray,_key,_value);
console.log('_someArray:');
console.log(JSON.stringify(_someArray));
//recovering the saved value with different separators
_key = 'a,a1,a21';
console.log(getObjectMultiLevelValue(_someArray,_key,','));
_key = 'c.c2.c21';
console.log(getObjectMultiLevelValue(_someArray,_key));

Let assume our object is
const data = {
//some other data
userInfo: {},
};
First, define a new property of that object
data.userInfo.vehicle = {};
then simply
data.userInfo.vehicle.vehicleType = state.userInfo.vehicleType;

Set JSON property with fully qualified string

This question achieves kinda the opposite of what I'm trying to do. Basically, I have this object:
var a = {
b: {
c: 'Foo'
}
}
What I need to do is set the value of c given the string 'b.c'. Unfortunately, I can't do this:
a['b.c'] = 'Bar'
As far as I can tell, the question above doesn't get me anywhere close as it just copies the values of the object properties so they can be read. It doesn't help me set the values of the object properties, however. Here's what I have so far:
var key = 'b.c'.split('.');
for (var i = 0; i < key.length; i++) {
// do something
}

Here's a functional way, is this what you need? It doesn't use the particular a[string] syntax but a function where you can pass the object string and the value to set:
var obj = { foo: { bar: { lol: { lulz: 69 } } } };
function setProp(obj, prop, value) {
var props = prop.split('.');
return [obj].concat(props).reduce(function(a,b,i) {
return i == props.length ? a[b] = value : a[b];
});
}
setProp(obj, 'foo.bar.lol.lulz', 'hello world');
console.log(obj.foo.bar.lol.lulz); //=> "hello world"

You have to intercept the last iteration of the loop, and from there assign instead of redefining your temp variable.
I adapted the answer to the question you linked to assign the value 2 to a.b.c:
var a = {
"b" : {
"c" : 1
}
}
var n = "b.c".split(".");
var x = a;
for(var i = 0; i < n.length; i++){
if(i == n.length-1) {
x[n[i]] = 2;
} else {
x = x[n[i]];
}
}
http://jsfiddle.net/Fuhbb/
This is pretty much what #Ian is doing in his jsfiddle. Intead of an if, he loops one step less, then deals with the assignment after the loop.

For the record, I eventually figured out another way to do this:
function setProperty(obj, props, val) {
if (obj[props[0]] instanceof Object) {
setProperty(obj[props[0]], props.slice(1, props.length), val);
return;
}
obj[props[0]] = val;
}
Call it like this:
a = {
b: {
c: 'Foo'
}
};
var whatever = 'b.c';
var props = whatever.split('.');
setProperty(a, props, 'Bar');

Implementing a yield iterator of object properties in JavaScript

I need a true iterator that will work like this:
var haystackObj = {
'needle': 'abc',
'prop2': {
'prop1': 'def',
'prop2': {
'needle': 'ghi',
},
'needle': 'jkl',
},
};
var needleKey = 'needle';
var iterator = {
next: function () {
/*
* WHAT CODE GOES HERE?
*
* Should return the next property, recursively, with the name
* equal to needleKey, of haystackObj.
*
*/
}
};
var value = iterator.next();
console.log(value); // -> 'abc'
value = iterator.next();
console.log(value); // -> 'ghi'
value = iterator.next();
console.log(value); // -> 'jkl'
I think this would be trivial with a for(k in o) and first-class continuations, but JS doesn't have those.
EDIT: I can only scan haystackObj once.
EDIT2: I am not looking for "a way to iterate through object properties." I am looking for an iterator of object properties. That is a huge difference. The problem is not as trivial as it may look at first glance.

Properties order is not guaranteed in JS. Different engines behave differently. (Some engines based on alphabetical order, other based on last added order.)
Your requirements are thus impossible to fulfill.
If you just wanted an iterator without minding the order, you could take a look at this question/answers: How to simulate JavaScript yield?
This is what the spec says about the properties order:
The mechanics and order of enumerating the properties (step 6.a in the first algorithm, step 7.a in the second) is not specified. Properties of the object being enumerated may be deleted during enumeration. If a property that has not yet been visited during enumeration is deleted, then it will not be visited. If new properties are added to the object being enumerated during enumeration, the newly added properties are not guaranteed to be visited in the active enumeration. A property name must not be visited more than once in any enumeration.
In reality however, you can expect a certain order from most browsers: Elements order in a "for (… in …)" loop
The only way I see to implement a fake generator (according to the fact that the order in reality suits you) would be to copy your object, and delete the scanned properties of the copy when needed. This'd mean you wouldn't rescan twice the same properties. Some code example:
var Iterator = function() {
var copy = $.extend(haystackObj, true);
// ^ using jQuery's extend for a quick function, but use w/e you want.
// Anyway keep it in a closure. This copy will have its properties deleted
// after each iteration.
return {
next: function next() {
var found = false,
needle;
for (var prop in copy) {
if (typeof copy[prop] === 'object') {
// Since next() doesn't take any argument...
// That's a bad solution. You should use an inner function
// to recurse. But I'm going to bed right now!
var copyCopy = $.extend(copy, true);
copy = copy[prop];
found = next();
copy = copyCopy;
}
else {
if (prop === needleKey) {
found = true;
}
}
if (found) {
needle = copy[prop];
}
// Delete the current property to simulate a real generator.
delete copy[prop];
if (found) {
return needle;
}
}
}
};
};
// Usage:
var iterator = Iterator();
iterator.next(); // "abc"
This code doesn't work (see jsfiddle), and I'm going to sleep. But you can see where it's going and how you could make something.

Assuming I understand you correctly, and bearing in mind that this is not a 'true yield', and putting all the code where you seem to want it,
var iterator = {
next: function () {
/*
* WHAT CODE GOES HERE?
*
* Should return the next property, recursively, with the name
* equal to needleKey, of haystackObj.
*
*/
var values=[], findneedles;
findneedles = function(o){
var k;
for(k in o){
if(k === needleKey){
values.push(o[k]);
}else if(typeof o[k] === 'object'){
findneedles(o[k]);
}
}
};
findneedles(haystackObj);
this.next = function(){
return values.shift();
};
return values.shift();
}
};

Although Florian Margaine's answer points out that the order of the properties are dependent on the js engine, this solution works in chrome. Took me a little bit of tweaking, but here it is http://jsfiddle.net/6zCkJ/3/:
Edited (this solution was done before OP said the tree can only be processed once)
var needleKey = 'needle';
var currIndex = 0;
var runningIndex = 0;
var getValueByIndex = function (obj) {
var objToSearch = obj || haystackObj;
for (var x in objToSearch) {
if (x == needleKey) {
if (runningIndex == currIndex) {
currIndex += 1;
return objToSearch[x];
}
runningIndex += 1;
} else if (typeof objToSearch[x] == 'object') {
var found = getValueByIndex(objToSearch[x]);
if (found) return found;
}
}
}
var iterator = {
next: function () {
runningIndex = 0;
return getValueByIndex(0);
}
};
Another approach which will only traverse the tree a single time is as follows http://jsfiddle.net/6zCkJ/6/. The catch is that you must load the values array whenever the needle is updated:
var currIndex = 0;
var valuesArray = [];
var loadValues = function (obj) {
var objToSearch = obj || haystackObj;
for (var x in objToSearch) {
if (x == needleKey) {
valuesArray.push(objToSearch[x])
} else if (typeof objToSearch[x] == 'object') {
loadValues(objToSearch[x]);
}
}
}
loadValues();
console.log(valuesArray);
var iterator = {
next: function () {
return valuesArray[currIndex++];
}
};
Edit: So far all answers posted here involve having to navigate the whole tree at least once or more which is not what the OP is looking for, including having to copy the object and remove properties as they are traversed. There is a solution though which involves marking the objects as they traversed with meta data which allows you to skip over the objects the next time they are encountered. Using my first approach it would be rather trivial to add these optimizations and hopefully accomplish what the OP is requesting.
Alright, so I couldn't resist trying to get this to work. Here is how I did it http://jsfiddle.net/6zCkJ/12/ . You can see that I am storing the found objects in the foundObjects object, where the key is made up of the path to that object so you can do a quick lookup to see if it has already been recursed over. The numFound is used to increment the running index properly. I have not tested this heavily, but it should be a good start:
var Iterator = function () {
var needleKey = 'needle';
var currIndex = 0;
var runningIndex = 0;
var foundObjects = {};
var getValueByIndex = function (obj,currentPath) {
var objToSearch = obj || haystackObj;
for (var x in objToSearch) {
currentPath += x + '_';
if (x == needleKey) {
if (runningIndex == currIndex) {
currIndex += 1;
if (!foundObjects[currentPath]) {
foundObjects[currentPath] = {
numFound: 0,
finished: false
};
}
foundObjects[currentPath].numFound += 1;
return objToSearch[x];
}
runningIndex += 1;
} else if (typeof objToSearch[x] == 'object') {
if (foundObjects[currentPath] && foundObjects[currentPath].finished) {
runningIndex += foundObjects[currentPath].numFound;
} else {
var found = getValueByIndex(objToSearch[x],currentPath);
if (found) {
return found;
}
}
}
if (!foundObjects[currentPath]) {
foundObjects[currentPath] = {
numFound: 0,
finished: true
};
}
foundObjects[currentPath].finished = true;
}
}
this.next = function () {
runningIndex = 0;
return getValueByIndex(0,'');
}
};
var iterator = new Iterator();
var value = iterator.next();

I'm going to answer this one for posterity.
In ECMAScript 6 we have a yield statement. But lets say you're nuts and you'd like to use this feature right now. Compiled using the traceur-compiler to your plain old JavaScript, we get the following.
Input:
var iterator = function* (object) {
for(var key in object) {
yield key;
for( k of iterator(object[key]) ) {
yield k;
}
}
};
var o = {
a: 10,
b: 11,
c: {
ca: 12,
cb: 13,
},
d: 14,
};
var res = [];
for( key of iterator(o) ) {
res.push(key);
}
res;
Output
var $__generatorWrap = function(generator) {
return $traceurRuntime.addIterator({
next: function(x) {
switch (generator.GState) {
case 1:
throw new Error('"next" on executing generator');
case 3:
throw new Error('"next" on closed generator');
case 0:
if (x !== undefined) {
throw new TypeError('Sent value to newborn generator');
}
case 2:
generator.GState = 1;
if (generator.moveNext(x, 0)) {
generator.GState = 2;
return {
value: generator.current,
done: false
};
}
generator.GState = 3;
return {
value: generator.yieldReturn,
done: true
};
}
},
'throw': function(x) {
switch (generator.GState) {
case 1:
throw new Error('"throw" on executing generator');
case 3:
throw new Error('"throw" on closed generator');
case 0:
generator.GState = 3;
throw x;
case 2:
generator.GState = 1;
if (generator.moveNext(x, 1)) {
generator.GState = 2;
return {
value: generator.current,
done: false
};
}
generator.GState = 3;
return {
value: generator.yieldReturn,
done: true
};
}
}
});
};
var iterator = function(object) {
var $that = this;
var $arguments = arguments;
var $state = 20;
var $storedException;
var $finallyFallThrough;
var $__0;
var $__1;
var $__2;
var $__3;
var $__4;
var $__5;
var key;
var $G = {
GState: 0,
current: undefined,
yieldReturn: undefined,
innerFunction: function($yieldSent, $yieldAction) {
while (true) switch ($state) {
case 20:
$__2 = [];
$state = 21;
break;
case 21:
$__3 = object;
$state = 23;
break;
case 23:
for (var $__4 in $__3) $__2.push($__4);
$state = 25;
break;
case 25:
$__5 = 0;
$state = 17;
break;
case 17:
if ($__5 < $__2.length) {
$state = 12;
break;
} else {
$state = 19;
break;
}
case 11:
$__5++;
$state = 17;
break;
case 12:
key = $__2[$__5];
$state = 13;
break;
case 13:
if (!(key in $__3)) {
$state = 11;
break;
} else {
$state = 15;
break;
}
case 15:
this.current = key;
$state = 1;
return true;
case 1:
if ($yieldAction == 1) {
$yieldAction = 0;
throw $yieldSent;
}
$state = 3;
break;
case 3:
$__0 = $traceurRuntime.getIterator(iterator(object[key]));
$state = 7;
break;
case 7:
if (!($__1 = $__0.next()).done) {
$state = 8;
break;
} else {
$state = 11;
break;
}
case 8:
k = $__1.value;
$state = 9;
break;
case 9:
this.current = k;
$state = 5;
return true;
case 5:
if ($yieldAction == 1) {
$yieldAction = 0;
throw $yieldSent;
}
$state = 7;
break;
case 19:
$state = -2;
case -2:
return false;
case -3:
throw $storedException;
default:
throw "traceur compiler bug: invalid state in state machine: " + $state;
}
},
moveNext: function($yieldSent, $yieldAction) {
while (true) try {
return this.innerFunction($yieldSent, $yieldAction);
} catch ($caughtException) {
$storedException = $caughtException;
switch ($state) {
default:
this.GState = 3;
$state = -2;
throw $storedException;
}
}
}
};
return $__generatorWrap($G);
};
var o = {
a: 10,
b: 11,
c: {
ca: 12,
cb: 13
},
d: 14
};
var res = [];
for (var $__1 = $traceurRuntime.getIterator(iterator(o)), $__0; !($__0 = $__1.next()).done;) {
key = $__0.value;
{
res.push(key);
}
}
res;
So yield statement in JavaScript, possible, but highly impractical.
What I actually ended up using
Usage example:
var object = {...};
var callback = function (key, value) {
// Do stuff...
return traverse.CONTINUE;
// or return traverse.STOP if you want the iteration to stop
};
traverse(object, callback);
Implementation:
var traverse = (function () {
var _traverse = function (object, callback) {
var key, value, command;
for( key in object ) {
value = object[key];
command = callback(key, value);
if( command === _traverse.STOP ) {
return _traverse.STOP;
}
command = _traverse(value, callback);
if( command === _traverse.STOP ) {
return _traverse.STOP;
}
}
};
_traverse.CONTINUE = 1;
_traverse.STOP = 2;
return _traverse;
})();

What's the fastest way to interpret a nested javascript object attribute accessor string?

Say I have a nested object structure like:
var o = { a: { b: { c: 1 } } };
and I have a an accessor String like "a.b.c".
What's the fastest function to return the specified nested value (to any depth [1..n])?
I.e. in this case, getNested(o, 'a.b.c') === 1 and getNested(o, 'a') === {b:{c:1}}.
What's the best implementation of getNested?

one more variant:
function getNested(obj, path) {
path.replace(/[^\.]+/g, function (p) {
obj = obj[p];
});
return obj;
}

I hate to give an answer without profiling the code myself, but given that eval is probably slow, and forEach is slower than just running through a for-loop, I would start with:
// precondtion: path is a nonempty string
function getNested(obj, path) {
var fields = path.split(".");
var result = obj;
for (var i = 0, n = fields.length; i < n; i++) {
result = result[fields[i]];
}
return result;
}
But I would test this against other approaches.
I don't think that trying to optimize away the array construction on split would be worthwhile, but this is only one thing to try if you are interested in the fastest way.
ADDENDUM
Here is a transcript so you can see it in action:
$ node
> function getNested(obj, path) {
... var fields = path.split(".");
... var result = obj;
... for (var i = 0, n = fields.length; i < n; i++) {
... result = result[fields[i]];
... }
... return result;
... }
> var o = { a: { b: { c: 1 } } };
> getNested(o, "a")
{ b: { c: 1 } }
> getNested(o, "a.b.c")
1
** ADDENDUM 2 **
So embarassing -- I forgot the var in front of result before. That might speed it up a bit!
Other things to try:
Forget about the "optimization" with n and just do the for-loop test with i < test.length (might be optimized away anyway)
Replace split with substrings and indexOfs
Do the split with a regex /\./ instead of a raw string "."

Maybe something like this:
function getNested(o, path) {
var parts = path.split('.');
var member = o;
while (member && parts.length) {
member = member[parts.shift()];
}
return member;
}
It's probably not the fastest possible solution, but might be a useful starting point.

try{
var prop=eval(string);
}
catch(er){
prop=undefined;
}

My approach
var o = { a: { b: { c: 1 } } };
var getNested = function(p) {
var t;
p.split('.').forEach(function(e) {
t = o[e] || t[e]
});
return t
}
you can try:
getNested('a.b.c')